Hitherto, an electric power saving network technology that reduces an electric power or an electric energy consumed by network apparatus by reducing a traffic amount on a network is known.
The traffic amount is represented by, for example, a throughput, namely a packet transfer amount (number of packets per unit time, packet per second (PPS)). Moreover, the electric energy is acquired as a total amount of accumulated products of electric power and time (watt second (W·sec) or Joule (J)). Note that, the electric power is simply used unless specific restriction is necessary in the disclosure of the specification.
As an example of the electric power saving network technology, there is such a network system that replicas of a content are arranged on a plurality of servers connected to a core network or a metro network, and the content is delivered from a server geographically close to a client apparatus used by a user. The electric power consumed by the network apparatus can be reduced by reducing the traffic amount passing through the network in this system.
A technology that caches the replicas of a content can reduce the traffic amount processed in the network by caching more contents on a server or a node close to the client apparatus used by the user, resulting in more reduction in network apparatus deployment and electric power consumption. However, the caching of a large number of contents generates the electric power consumption and a cost accompanied by the memory use and the apparatus deployment. Therefore, it is necessary to take into consideration a correlation between the reduction in the electric power and the apparatus deployment as a result of the reduction in traffic amount, and the increase in the electric power and the cost accompanied by the content caching.
In recent years, attention has been paid on the content centric networking (CCN) technology that adds a cache functionality to nodes which construct a network, thereby alleviating a restriction on a cache allocation of contents. In a network to which the CCN technology is applied, replicas of a content are cached on nodes constructing a core network or a metro network. Then, a traffic amount flowing into the network can be reduced by delivering the content cached on the node, thereby reducing an electric power consumed by network apparatus and the apparatus deployment cost.
The following are related arts to the invention.
[Patent document 1] Japanese Patent Laid-Open Publication No. JP 2003-122658
[Patent document 2] Japanese Patent Laid-Open Publication No. JP 2003-280975
[Patent document 3] Japanese Patent Laid-Open Publication No. JP 2005-031987
[Patent document 4] Japanese Patent Laid-Open Publication No. JP 2011-176595
[Non-patent document 1] Energy Efficient Content Locations for In-Network Caching, Satoshi Imai, Kenji Leibnitz, Masayuki Murata, in proceeding of 18th Asia-Pacific Conference on Communications—APCC 2012, at Jeju Korea